ADT-Automatic Double Tracker Simulator

[LyleCaldwell]

I would suggest the delay should range from 20-60ms, depending on how pronounced you want the effect.  The 10-20ms range will sound too much like flanging, I would think.  Definitely some mono phase cancellation.

I'm still plotting my effect, I'm choosing to skip over all this raffle.  No offense meant to anyone who participated in the spam


So, here's my proposal:

Vibrato-pretty fast, and shallow,
Delay-hook the delay length up to an LFO that varies between 10-20 ms or so.
Chorus-Speed undetermined..how deep too?  I'd say pretty slow though, and medium depth.  What are your opinions?

So this would be my proposed setup:

Code Select Expand

   in
     |
     |
   panner
   |    |
  dry  wet(effects)
   |    |
   \    /
     out
      |
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Now, questions I have that I'd appreciate some info on:

Should the effects be put in series or parallel?  And if in series, what order would be optimum?
General info on LFO speeds, etc.  Should there be one LFO for all?  Should certain effects share an LFO?  What do you guys think?


Thanks!

[rockgardenlove]

Alright, thanks man
Really appreciate it.
Still have a few questions gone unanswered though, namely chorus speed, and vib speed.

Would an overall volume LFO be worthwhile?  Just to give it a bit of an overall less predictable trem sound at the same time?

[LyleCaldwell]

I don't think you'll need to do chorus AND vibrato.  Just LFO the delay time and slightly LFO the pitch and the rest should take care of itself.  I also don't think you need any trem - there will be phase relationships changing all the time, with some frequencies dipping and others accentuating, so there will be perceived volume fluctuations without doing an actual trem effect.

But if you do want some chorusing, I wouldn't LFO the chorus - just clone the output of the wet LFO and delay it by 30ms or so (no feedback) for a nice stereo spread.

[rockgardenlove]

Alright...

So far I've been considering using the PT-80 delay, would you say that's a good choice?  Or might it be better to use a AD-3208 delay because its analog?  (Both are at GGG.)

[Dave_B]

Tom Scholz did some work along these lines too.  Here's the patent for his reverb / doubler.

[rockgardenlove]

Interesting...with my limited electronic abilities, one of the simpler forms seems to be just a variable delay.

[rockgardenlove]

Alright, so just thought of something else.

Say if I wanted to use it for vocals, would I need any extra fancy stuff?  I don't need phantom power, I just want to use a Shure '58 or so. 

Also, if I wanted to send it the output from my Presonus Firebox(recording interface) and then loop it back into an input, would that require extra work?  Something to clear up possible impedence issues?  I think a standard "line out" is usually lower impedence than a guitar pickup. 

Thanks!

[stm]

To put it in physical terms, the tape delay has the following parameters to take into account:

a) Time delay -- between 25 and 75 msec
b) Frequency response with slightly less highs -- the antialias filters on the BBD take care of this aspect
c) Eventual compression effect of the tape recording -- again the BBD introduces some compression
d) Wow and flutter -- here is the key

Wow are slow fluctuations that can be associated to the speed servo control system. These are expected to be slow and shallow, thus a LFO around 1 Hz with shallow modulation will do.

Flutter are faster fluctuations that can be associated to the mechanical tape transport mechanism (pinch roller, elasticity of the rubber bands involved, gears, etc.)  This can be implemented as one or more faster LFO's, or as a pseudo random LFO.

Combining the aforementioned LFO's into a single modulating signal might do the trick. The key is that the wow and flutter LFO's must be asynchronous.

[rockgardenlove]

So the "wow" should be slow, that makes sence.  I was considering using a chorus for the "wow"...would that be a good choice?  What kind of effect should be applied do you think?

And for the "flutter" effect, I was thinking a vibrato, going fast, and being set really shallow...sound good?

And I'd top that all over with that LFO'd analog delay?  Does that sound right?

[rockgardenlove]

Bump wooples!

[stm]

Hi,

What I meant is use a single BBD, like an MN3008 or BL3208 would be great here due to the larger delay than a typical MN3007 et al.

You need at least two LFO's, one slow, one fast.  Mix them and use this compound signal to modulate the BBD clock.

Last but not least, mix the dry signal with the delayed signal and you are set.

As an idea, the slow LFO could be sinusoidal, while the faster one could be a filtered squarewave (pseudo triangle) perhaps for a more drammatic effect.  YMMV.

As a starting point, you may consider a chorus circuit but with two different LFOs that simoultanueously modulate the BBD Clock IC.  A compander on the wet signal might be advisable for optimum noise performance.  Again, YMMV.

Cheers.

[DuncanM]

Or even use an LFO, the speed of which is modulated by a second LFO - this gets rid of the regular modulation that we associate with "chorus" or "flange". Might be more subtle and "organic"...
Slightly different from just adding the output of two LFO's together.

[rockgardenlove]

^Alright, thanks guys.  I'll take all that stuff into consideration.

If I use a chorus too, I'm assuming the chorus should come before the delay?

[LyleCaldwell]

No, the chorus should only be applied to the delay.

[zachary vex]

i read through the whole thread and never found the word "capstan."  as i recall, Geoff E. taped lumps around the capstan of one machine to introduce variations in tape speed by simply changing the capstan's diameter unevenly.

[LyleCaldwell]

Never seen that in any interview.  Numerous people have specifically mentioned the knob controlling the voltage fed to the second tape deck.

[TELEFUNKON]

i read through the whole thread and never found the word "capstan." 

in reply#47 stm mentioned the "pinch roller" (reminded me of "capstan"):

Flutter are faster fluctuations that can be associated to the mechanical tape transport mechanism (pinch roller, elasticity of the rubber bands involved, gears, etc.) 

[SeanCostello]

i read through the whole thread and never found the word "capstan."  as i recall, Geoff E. taped lumps around the capstan of one machine to introduce variations in tape speed by simply changing the capstan's diameter unevenly.

Wow. That is a neat idea. I have seen something similar in a Donald Leslie patent, where a frequency shifter (based upon something mechanically rotating, of course) is driven by a "cam" that is irregularly shaped, in order to introduce a quasi-random deviation to the shift amount.

Makes me wonder if Boards of Canada do something similar to their tape processing...

Sean Costello

[MartyMart]

Makes me wonder if Boards of Canada do something similar to their tape processing...

Sean Costello

HA ! they are the "Kings" of modulation ! 
Couldn't this be done with the following three pedals :
A "Y" lead to split the signal ( a wet and a dry feed)
A delay pedal set to around 60ms - no repeats
A chorus, slow with blend at 100%
Another, or phase with blend at 100% for vibrato set faster 
Both signals back together with "Y" lead No2 or a mixer stage ...?

MM.

[Mark Hammer]

Even "lumps" on a capstan will result in a certain periodicity, though clearly they will result in an irregular wavform (i.e., not the same old triangle).  Perhaps, from an electronic perspective, the optimal solution is to use either a noise-based CV/modulation source (like the Maestro S&H), or several unsynced LFOs mixed together (as STM suggests).